Synthesis of new gold(I) thiolates containing amino acid moieties with potential biological interest.

The reaction of the gold(I) complex [Au(SpyCOOH)(PPh3)], which contains nicotinic acid thiolate, with several amino acid esters such as glycine methyl ester or the enantiomerically pure L isomers of alanine methyl ester, phenylalanine methyl ester, valine methyl ester, methionine methyl ester, and proline methyl ester produces the gold(I) derivatives with the new thiolate containing amino acid ester ligands [Au{SpyCONHCH(R)COOMe}(PPh3)]. The reaction of these amino acid ester derivatives with LiOH in methanol and acidification with KHSO4 until pH 3-4 afford the corresponding acids, which are water-soluble species. These amino acid compounds can be further coupled with other amines, such as, for example, isopropylamine, to give the corresponding amide derivatives. The species with glycine methyl ester and valine methyl ester have been characterized by X-ray crystallography, showing, in the second case, only one of the enantiomers, which proves that retention of the configuration after reaction occurs.